Two-Stage Detergent Dosing for Drum Washing Machines in Hard Water
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Solution Overview
Problem
Existing textile washing processes in drum washing machines do not achieve optimal cleaning performance, particularly in high water hardness conditions, due to inadequate interaction and timing of detergent compositions.
Innovation Solution
A multi-stage washing process in drum washing machines involving a first detergent composition with specific surfactants and a second detergent composition containing high-concentration protease enzymes, dosed at different times during the main wash cycle based on textile weight and water hardness, optimizing the interaction and effectiveness of the detergents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single detergent composition is used throughout the main wash cycle, then the washing process is simple to operate, but cleaning performance is suboptimal especially in high water hardness conditions
Solution Approach 1:
The washing process is segmented into two distinct dosing stages: first dosing surfactant-containing detergent composition at the beginning of the main wash cycle, and second dosing protease-containing detergent composition during the rinsing phase. This segmentation allows each detergent composition to perform its optimized function at the appropriate time, improving cleaning performance while maintaining operational simplicity through automated dosing.
Solution Approach 2:
The surfactant-containing detergent composition is dosed in advance at the beginning of the main wash cycle to prepare for soil removal. The protease-containing detergent composition is then dosed later during the rinsing phase to complete the cleaning process. This preliminary action ensures optimal conditions for each detergent type to function effectively.
2Reliability
If detergent compositions are dosed simultaneously, then the dosing system is simple, but cleaning efficacy is reduced due to suboptimal interaction between detergent components
Solution Approach 1:
The dosing process is divided into two time-separated stages: first dosing surfactant-containing composition at 0-10% of main wash cycle time, and second dosing protease-containing composition during the rinsing phase (11-99% of main wash cycle time). This temporal segmentation allows optimal interaction between detergent components while maintaining efficient cycle timing.
3Reliability
If detergent dosing is optimized for high water hardness conditions, then cleaning performance improves in hard water, but performance in soft water conditions deteriorates
Solution Approach 1:
The dosing strategy uses parameter changes in timing and composition type: surfactant-containing composition is dosed first to handle general soil removal, and protease-containing composition is dosed later to target protein-based soils that are particularly problematic in hard water. This parameter-based approach maintains adaptability across different water hardness conditions while optimizing performance in hard water.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves above-average cleaning results, especially in high water hardness conditions, by enhancing the cleaning performance of surfactants and protease enzymes, resulting in improved laundry cleaning efficiency.
Implementation Method 1
Introducing a second detergent composition comprising, based on its total weight, i) at least 4 wt% active protease protein
Implementation Method 2
a second detergent composition comprising, based on its total weight, i) at least 4 wt% active protease protein
Implementation Method 3
a first detergent composition comprising i) at least 30 wt% surfactant
Data Source
AI summary
Washing process for textiles in a drum washing machine, comprising the steps of: a) providing a washing machine with a washing program comprising a main wash cycle of duration tw; b) introducing textiles into the washing machine's treatment chamber; c) introducing an aqueous liquor into the washing machine's treatment chamber; d) introducing a first detergent composition, comprising at least one surfactant, into the washing machine's treatment chamber during the main wash cycle at a time point between 0 and 10% tw; e) introducing a second detergent composition, comprising, based on its total weight, i) at least 4 wt% active protease protein; ii) at least 80 wt% of a liquid carrier into the aqueous liquor of the main wash cycle at a time point between 11 and 99% tw.